CHICAGO - US President Barack Obama congratulated Republican rival Mitt Romney on Tuesday for running a hard-fought race for the White House and expressed confidence he would win re-election during a stop at a local campaign office to thank volunteers on Tuesday."I ... want to say to Governor Romney congratulations on a spirited campaign. I know that his supporters are just as engaged and just as enthusiastic and working just as hard today," Obama said as volunteers made phone calls encouraging supporters to get to the polls."We feel confident we've got the votes to win, but it's going to depend ultimately on whether those votes turn out. And so I would encourage everybody on all sides just to make sure that you exercise this precious right that we have that people fought so hard for us to have."Obama made calls to volunteers from the campaign office to thank them for working for his re-election."I expect that we'll have a good night, but no matter what happens, I just want to say how much I appreciate everybody who supported me, everybody who's worked so hard on my behalf."